With the wide application of intelligent terminals, there has been an ever increasing demand for network traffic, and in order to meet the needs of people to access the internet anytime and anywhere, performance of the network system must be improved, based on which the wireless fidelity (Wi-Fi) system in a wireless local area network evolved from IEEE 802.11a/b to 802.11g and 802.11n, and then evolved from 802.11g and 802.11n to 802.11ac.
IEEE 802.11n is provided with distributed coordination function (DCF, distributed coordination function), point coordination function (PCF, point coordination function), hybrid coordination function (HCF, hybrid coordination function), and enhanced distributed channel access (EDCA, enhanced distributed channel access) technology. As to the distributed coordination function, users access the channel through competition, and only the user that acquires a channel is allowed to transmit data; as to the point coordination function, user begins to transmit data after receiving a poll from an access point (AP, access point), where the transmission duration is one frame; and as to the hybrid coordination function, user begins to transmit data after receiving a poll from the AP, where the transmission duration is one or multiple frames.
During the research and practice on the prior art, the inventor finds that, in the existed technology, the AP can query only one user every time to find out whether scheduling is requested, in other words, the AP can only query one user each time to find out whether there is data to transmit, thus increasing the data transmission delay for the user, and lowering the service quality of the system.